This invention relates generally to improvements in fuel cell fuel delivery arrangements for use in combustion tools, and more specifically to actuators for delivering the appropriate amount of fuel for use by a combustion tool during the driving of fasteners, as well as associated combustion tools and their components.
As exemplified in Nikolich U.S. Pat. Nos. 4,403,722, 4,483,474, 4,522,162, and 5,115,944, all of which are incorporated by reference, it is known to use a dispenser such as a fuel cell to dispense a hydrocarbon fuel to a combustion tool, also known as a combustion gas-powered tool, or a combustion gas-powered fastener-driving tool. In particular, a fuel cell of this type is described in Nikolich U.S. Pat. No. 5,115,944, listed above.
A design criterion of such fuel cells is that only a desired amount of fuel should be emitted by the fuel cell for each combustion event. The amount of fuel should be carefully monitored to provide the desired combustion, yet in a fuel-efficient manner to prolong the working life of the fuel cell. Prior attempts to address this dosage factor have resulted in fuel metering valves located in the tool (U.S. Pat. No. 5,263,439) or attached to the fuel cell (U.S. Pat. No. 6,302,297), both of which are also incorporated by reference.
Another design consideration of cell-mounted metering valves is that the fuel metering valve mounted on the fuel cell emits fuel at an approximate right angle to the axis of the fuel cell and the main fuel cell stem valve. To obtain a measured dose of fuel, the tool actuator exerts a force on the fuel metering valve which is transverse to the axis of the cell valve stem. This periodic loading is considered detrimental to the working life and sealing efficiency of the fuel cell stem valve.
Copending, commonly assigned U.S. Ser. No. 10/827,551, incorporated by reference, discloses a fuel metering valve mounted internally within the fuel cell. Such an arrangement addresses the design considerations listed above, as well as others.
However, there is a need for reconfiguring the corresponding combustion tools, both new production and tools existing in the field, to accommodate the new fuel cells and efficiently dispense fuel when needed. There is also a need for providing an actuation system which can withstand repeated combustion cycles in the often rigorous working environment of such combustion tools.
There is a further need for an improved combustion tool fuel cell construction which reduces the number of sealing locations and the periodic loading on the main fuel cell valve stem.